The present invention relates to a method of depositing coatings on a substrate, particularly heat reflective coatings useful in making high temperature solar collector absorbers. The invention also relates to apparatus for practicing such method, and solar collectors made in accordance with such method.
One known form of high temperature solar collector absorber includes an inner tube for conducting the working fluid and having an absorber coating thereon, and an outer transparent tube coaxial with the inner tube and separated therefrom by an annular vacuum space. The solar collector further includes a mirror receiving the solar radiation and reflecting it through the outer transparent tube onto the absorber coating of the inner tube for heating the working fluid flowing through the inner tube. The working fluid may thus be heated to very high temperatures, over 200.degree. C. Because of these high temperatures, the absorber coating may be of the selective type to reduce radiation losses from the working fluid back to the atmosphere.